92697 2012-07-30 17:44:33 -0700 RenderObject needs a fast-path for removeAllChildren 2012-10-18 11:48:54 -0700 1 1 1 Unclassified WebKit Layout and Rendering 528+ (Nightly build) Unspecified Unspecified NEW P2 Normal --- 98281 98336 99741 92258 1 eric webkit-unassigned jamesr jchaffraix kling simon.fraser oldest_to_newest 682570 0 eric 2012-07-30 17:44:33 -0700 RenderObject needs a fast-path for removeAllChildren Looking at the sample of the benchmark attached to bug 92258. We see nearly 10% of total time (on a 300x300 grid sample), spent under ContainerNode::removeChildren() tearing down the associated rendering tree. Each renderer goes through and tell its ancestor chain that it's dying, and marks the view as needing repaint for its rect. We spend a bunch of time computing those repaint rects, and walking up/down the ancestor chain. Just like how we have a "fast path" for removing subtrees in the DOM, we need some smarter logic for removing subtrees in the rendering tree. At least in the non-positioned, flow cases, we should be able to have a single repaint rect instead of all this nonsense.